Error Message: HTTP/1.1 Error 400 - Bad Request

• Microsoft Internet Information Services version 5.0

SYMPTOMS

When a GET request is submitted to a Web server configured with Custom Error pages, the Web server sends the following error message to the client browser:

HTTP/1.1 Error 400 - Bad Request

CAUSE

This behavior is expected when the GET request itself cannot be parsed because of some kind of packet corruption. If you send a bad request to the IIS Web server, the Custom Errors functionality is not invoked, which causes the "HTTP/1.1 Error 400 - Bad Request" error message.

RESOLUTION

If the contents of a GET request are corrupt, then the server is unable to determine the URL or the host to which the GET request should be sent. IIS is unable to retrieve the host information from the GET request packet in order to look up the meta data for the custom error. This is by design. Errors that result from severely corrupted GET requests are not customizable.

To more completely determine what may be occurring, obtain a network capture of the communication packets between the client receiving the error and the Web server itself. Use the Microsoft Network Monitor utility to capture network packets for analysis. For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

Q148942 How to Capture Network Traffic with Network Monitor

Additional query words:

Keywords : kbWinOS2000
Version : winnt:5.0
Platform : winnt
Issue type : kbprb